In this grant request we propose to study the functional and developmental consequences in the retina of the inactivation of enzymes involved in the metabolism of gamma aminobutyric acid (GABA) and dopamine. This work will revolve around the use of highly selective irreversible inactivators of glutamate decarboxylase, DOPA decarboxylase and to a lesser extent GABA-transaminase and monoamine oxidase. In addition, using radiolabelled glutamate decarboxylase inactivators we plan to map GABAergic neurons in the retina. We will also map those neurons capable of producing DOPA decarboxylase with a specific irreversible DOPA decarboxylase inactivator. The functional and mapping studies will be done on the retinas of the chicken, rabbit and goldfish and the developmental studies in the chick embryo. The enzyme inactivator used will include alpha-methyl trans dehydroglutamic acid, alpha-fluoromethylglutamic acid derivatives, and gamma-acetylenic GABA or glutamate decarboxylase inhibition; S-alpha-fluoromethyl DOPA decarboxylase inhibitor, gabaculine a GABA-transaminase inhibitor, and pargyline as a monoamine oxidase inhibitor.